Molecular biology techniques have revolutionized the ability of reproductive biologists to address specific physiological questions in a rapid, sensitive manner. This approach, however, often requires a large time investment to acquire appropriate expertise and equipment, additional time commitments to keep current in a rapidly advancing field, and critical attention to quality control for even the most routine and repetitive techniques. A major cost for many molecular experiments is the labor involved to provide dependable reagents and probes. A centralized, well-equipped core is the most efficient and economical way to provide recombinant DNA methodology and reagents for projects to pursue innovate molecular work in reproductive medicine. The objective of the Molecular Core is to provide services, expertise, and equipment to research projects addressing clinical and basic questions in reproduction. Three research projects within the U54, and five additional projects approved by the Reproductive Science Branch require access to the Core for routine services of probe labeling (end-label, random priming, and single-strand RNA riboprobes), DNA isolation, plasmid growths and purification, DNA sequencing, and DNA fragment isolation and subcloning procedures. The core director and personnel will provide advice and expertise on the design of probes and expression vectors, various RNA and DNA quantitation methods, and specialized techniques such as library screening. Core personnel will provide timely, quality-controlled service and reagents to approved projects on a priority basis. Approve investigators can access the core for specialized equipment to perform more advanced techniques on a availability basis. Finally, Core personnel will continue to improve and develop additional services and procedures as required by projects accessing the core, and update current services to provide the most sensitive, precise, and cost-effective reagents.